diff --git a/spec/integration/support/application.rb b/spec/integration/support/application.rb
index 7f261e28..d3983ff5 100644
--- a/spec/integration/support/application.rb
+++ b/spec/integration/support/application.rb
@@ -65,7 +65,6 @@ def self.respond_with(options = {})
 
     map "/multipart" do
       run lambda { |env|
-        boundary = 'mimepart_boundary'
         message = Mail.new
         xml_part = Mail::Part.new do
           content_type 'text/xml'